Partial evaluation specializes a function with respect to
arguments that have known values. Given a program P(x, y)
where the values of variables x are constant, a specializing function
mix transforms P(x, y) &rarr Px(y) such that
P(x, y) = Px(y) for all inputs y. Px(y) may
be shorter and faster than P(x, y) . We call x static data
and y dynamic data. .